/// <summary>
/// Perform a difference between the path of two loops.
/// </summary>
/// <remarks>This function assumes the left and right loops have only one
/// path that's a closed island.</remarks>
/// <param name="left">The island being subtracted from.</param>
/// <param name="right">The island being subtracted.</param>
/// <param name="onIslA">A node that's on the island, or null if no geometry
/// is left afterwards.</param>
public static void Difference(
BLoop left,
BLoop right,
out BNode onIslA)
{
// we always remove B, which may contain extra stuff from
// subtraction shapes that didn't find a target to remove.
PerIslandBoolean(
left,
right,
Difference,
out onIslA,
true);
right.Clear();
RemoveLoop(right, true);
}
/// <summary>
/// Perform an intersection operation between two islands using a reflow strategy.
/// </summary>
/// <param name="left">The collection of islands for the operation.</param>
/// <param name="right">The other collection of islands for the operation.</param>
/// <param name="onIslA">An output node that exists on the remaining path(s).</param>
/// <param name="removeRight">If true, remove the contents of the right loop parameter after
/// the operation.</param>
public static void Intersection(BLoop left, BLoop right, out BNode onIslA, bool removeRight)
{
onIslA = null;
// Sanity check on geometry, try to union each loop with its islands
// so there's no overlapping regions within them.
List <BNode> rightIslands = right.GetIslands();
if (rightIslands.Count >= 2)
{
for (int i = 1; i < rightIslands.Count; ++i)
{
List <BNode> RSegsA = new List <BNode>(rightIslands[0].Travel());
List <BNode> RSegsB = new List <BNode>(rightIslands[i].Travel());
Union(right, RSegsA, RSegsB, out onIslA, true);
}
}
List <BNode> leftIslands = left.GetIslands();
if (leftIslands.Count >= 2)
{
for (int i = 1; i < leftIslands.Count; ++i)
{
List <BNode> LSegsA = new List <BNode>(leftIslands[0].Travel());
List <BNode> LSegsB = new List <BNode>(leftIslands[i].Travel());
Union(right, LSegsA, LSegsB, out onIslA, true);
}
}
leftIslands = left.GetIslands();
rightIslands = right.GetIslands();
foreach (BNode leftIsl in leftIslands)
{
List <BNode> leftIslandSegs = new List <BNode>(leftIsl.Travel());
foreach (BNode rightIsl in rightIslands)
{
List <BNode> rightIslandSegs = new List <BNode>(rightIsl.Travel());
Intersection(
left,
leftIslandSegs,
rightIslandSegs,
out onIslA);
}
}
foreach (BNode bn in leftIslands)
{
bn.RemoveIsland(false);
}
foreach (BNode bn in rightIslands)
{
bn.RemoveIsland(false);
}
// TODO: For each island left, we need to see if there's
// any shapes being fully contained by the other side.
if (removeRight == true)
{
right.Clear();
RemoveLoop(right, true);
}
}